The transforming growth factor-beta superfamily of growth and differentiation factors encompasses a group of proteins affecting a wide range of differentiation processes. Because many of these differentiation processes are essential for normal embryonic development, an understanding of the expression and function of these family members would provide insights into how normal regulatory events induced by these factors may go awry to perturb fetal development and how the actions of these factors at ectopic sites or at inappropriate times during adult life may contribute to the generation of a cancer cell. Previous work from this laboratory has identified eight novel mammalian members of this superfamily. Three of these novel factors (GDF-5, GDF-6, and GDF-7) form a new subgroup within the larger superfamily. One of these (GDF-5) appears to be expressed at high levels in adult uterus and in mid-gestation embryos. The overall aim of this proposal is to investigate the roles that this new subfamily plays both during embryonIc development and in adult tissues. The specific aims are to Isolate additional members of this subfamily; to isolate and sequence full-length cDNA clones encoding GDF-5, GDF-6, and GDF-7; to raise antibodies against each of these factors; to determine their patterns of expression in embryos and in adult tissues using immunohistochemical and in situ hybridization methods; to purify GDF-5, GDF-6, and GDF-7 proteins from mammalian cells engineered to overproduce these factors; and to determine the distribution of their receptors. The structural homology between these new factors and the other family members suggests that GDF-5, GDF-6, and GDF-7 may play important roles in mediating developmental decisions related to cell differentiation. The expression of GDF-5 in the uterus suggests that it may be involved either directly or indirectly in regulating early embryogenesis. By analogy with other family members, these new family members have the potential to be used for both diagnostic and therapeutic applications in a variety of clinical settings.